The present invention relates to an antiperspirant composition, and more particularly, to an alcohol-based antiperspirant stick composition containing an acidic antiperspirant active compound in the presence of a gelling agent wherein the composition is stable at room temperature as well as at elevated temperatures.
The art is replete with formulations of stick-type cosmetics for various uses, such as antiperspirants and deodorants. The specific stick-type formulation varies depending upon such factors as the intended use, the "active" ingredient to be incorporated, and the part of the body to which the stick-type formulation is to be applied. As is well known in the art of antiperspirants, there are three main types of antiperspirant stick formulations, namely, compressed powdered sticks, gel sticks and wax sticks While each of these types of formulations has advantages depending upon the particular application, each formulation also possesses several disadvantages. For example, compressed powdered sticks are often brittle and hard and leave an aesthetically unacceptable dust upon application. Similarly, wax sticks also yield aesthetically unacceptable products due to factors such as hardness, greasiness and stickiness.
In the past, antiperspirant sticks of the gel type have been typically based on alcoholic or hydroalcoholic systems which have been gelled with sodium stearate (soap). However, ordinary aluminum salts are incompatible with a soap-alcohol system, resulting in the formation of insoluble soaps which prevent solidification or gelling of the stick. This result is undesirable and defeats the purpose for which such an antiperspirant stick is directed. Although a sodium aluminum chlorohydroxy lactate complex has been found to be compatible with typical soap-based sticks, such a complex merely functions as a deodorant as it provides only from about 10-12% sweat reduction. Since gel-type sticks have advantages over both compressed powder and wax sticks in that they leave very little residue or dust and provide a vehicle which glides easily over the skin surface, it would be desirable to have an alcohol-based antiperspirant stick composition which provides improved sweat reduction while maintaining a stable gel.
Several attempts have been made to overcome these disadvantages. For example, Roehl et al, U.S. Pat. No. 4,346,079 and Roehl et al, U.S. Pat. No. 4,154,816 include the use of dibenzaldehyde monosorbitol acetal (DBMSA) as a gelling agent to produce a more stable solid antiperspirant gel. Nevertheless, it has been found that such antiperspirant compositions, while avoiding the use of soaps, may produce antiperspirant compositions having aesthetically unacceptable stickiness. Further, such antiperspirants are not stable upon extended exposure to temperatures exceeding room temperature. As a result, there is a need for an antiperspirant composition that is not only stable at elevated temperatures, but also possesses aesthetically acceptable features such as hardness and clarity or translucentness.
In the past, antiperspirant compositions of the gel type have been unstable at elevated temperatures and even at room temperature. To that end, Schamper et al, U.S. Pat. No. 4,518,582, provide an antiperspirant composition containing a dibenzyl monosorbitol acetal gelling agent in the presence of an antiperspirant active metal salt which is taught to be stable at elevated temperatures. Schamper et al, however, require the addition of a gel stabilizer to prevent or retard deterioration of the gelled compositions at such temperatures. The inclusion of such gel stabilizers causes the antiperspirant to be hazy or cloudy which is aesthetically unacceptable. Furthermore, past antiperspirant compositions typically use excessive amounts of monohydric alcohols, such as ethanol, which tend to deteriorate and desolidify or liquidate the antiperspirant composition, especially at elevated temperatures. Additionally, the monohydric alcohol potentially can react with the dibenzyl monosorbitol acetal to form a different acetal, thereby decreasing the antiperspirant properties of the composition. It would therefore be desirable to have an antiperspirant composition which is stable at room temperature as well as elevated temperatures without the use of a gel stabilizer.
Other antiperspirant sticks currently in wide use are based on volatile silicone oil, stearyl or cetyl alcohol and aluminum chlorohydrate. Such antiperspirant compositions are relatively efficient, easy to apply, and have non-sting properties. However, these antiperspirant compositions also suffer from several drawbacks. For example, those antiperspirant compositions do not provide uniform settling of the components of the composition, which is caused by the lack of solubility of the inorganic salt component in the molten wax or gel phase. Uniform settling or distribution of all the components in the antiperspirant composition is extremely important since it is required by the Food & Drug Administration (FDA) for Over-The-Counter (OTC) drugs. Another disadvantage of these antiperspirant compositions relates to aesthetics in that they leave a white residue which is undesirable. Finally, as stated above, past antiperspirant compositions typically use large amounts of monohydric alcohols, such as ethanol, which lead to instability and produce unacceptable odors necessitating the incorporation of excess quantities of fragrances to mask such undesirable odors.
Accordingly, the need exists in the art for an alcohol-based antiperspirant stick composition of the gel type which does not contain gel stabilizers and excessive amounts of monohydric alcohols yet remains stable at room temperature as well as at elevated temperatures. There is also a need in the art for an antiperspirant composition in which the individual constituents are uniformly distributed upon gel formation. Finally, there is a need for a more inexpensive antiperspirant composition which has improved sweat reduction properties while providing aesthetically desirable features such as a high degree of clarity or translucentness as well as being substantially odorless.